Research On The Direct Liquefaction Of Coconut Fiber For The Preparation Of Bio-based Polyurethane Buffer Packaging Foam Materials

The conversion and utilization of biomass is an important guarantee for green and sustainable development.As an important agricultural and forestry by-product biomass resource,most of coconut fiber(CF)is currently discarded,incinerated and used with low added value,which not only causes waste of resources,but also damages urban landscape and living environment.Polyurethane buffer packaging foam has excellent performance and great application potential,but it is limited by the source of raw materials,the viscosity of the foaming composition and environmental issues.In this work,the biomass liquefaction technology was used to directly liquefy CF into petroleum-based polyol alternatives that could increase its application value.And the bio-based polyurethane buffer packaging foam(BPUF)material was prepared by using the CF liquefaction products through the optimization of the formula,which provided an effective way and method for the high value utilization of CF biomass resources and the green development of buffer packaging foam.Firstly,based on the analysis of the raw material composition of the CF,the effects of multiple variables on the liquefaction reaction of the CF and its liquefaction products for the preliminary synthesis of polyurethane foam materials were examined through single-factor experiments,and the better reaction conditions as well as the properties of the liquefied products were determined.The results showed that the mixed polyol was used as the liquefaction reagent(PEG 400:G=4:1,mass ratio),the liquid-solid ratio was 6:1(mass ratio of liquefaction reagent to CF),and 2%concentrated sulfuric acid(based on the total mass of the liquefaction reagent)as a catalyst,and a reaction at 160 ?for 80 min under normal pressure could achieve a better liquefaction effect.Under these conditions,the liquefaction reaction residue rate was 6.5%,the liquefaction products had a hydroxyl value of 345.9 mgKOH/g,an acid value of 18.2 mgKOH/g,and a viscosity of 360 mPa·s(25?).The characterization and analysis of liquefaction products exhibited that lignocellulose in CF was deeply degraded,and a liquefied product rich in hydroxyl groups was obtained,which could be used as a raw material for synthetic polyurethane foam materials.Secondly,using the obtained CF liquefaction products under better conditions as a substitute for part of the petroleum-based polyol raw materials,the BPUF was synthesized,and the effect of the foaming formula on the properties of BPUF was investigated.The results demonstrated that at an isocyanate index of 1.1,35 portions of CF liquefaction products,32.5 portions of polyether polyol A and polyether polyol B,and 5 portions of deionized water as a blowing agent,1.9 portions of compound catalyst and 0.9 portions of surfactant(all based on the total mass of poly ether polyol)could be a preferred formula.Under this formula,the obtained BPUF foamed well,with an average pore diameter of 427 ?m and an uniform pore size distribution.The BPUF had excellent comprehensive performance,with a density of 20.3 kg/m3,a compressive strength of 40.2 kPa,a compression modulus of 766 kPa,and a minimum cushioning coefficient of 2.27.Finally,in order to further efficiently utilize CF biomass resources,the CF liquefaction products were post-processed,and the effects of post-processed CF liquefaction products with different contents on the properties of BPUF were explored.Results indicated that the CF liquefaction product without slag-neutralization(NN),slag-neutralization(NZ),and slag-neutralization(BPZ)could be respectively used as a raw material for the synthesis of BPUF,and the BPUF could achieve better overall performance when they replaced 15,45 and 65 portions of petroleum-based polyols,respectively.When different post-processed CF liquefaction products were added,the thermal stability of BPUF was improved to a certain extent.When 65 portions of BPZ was used instead of petroleum-based polyols,BPUF with excellent comprehensive properties could be obtained,and CF biomass resources could be effectively used.In detail,the BPUF prepared by adding 65 portions of BPZ as a petroleum-based polyol substitute had an average pore diameter of 326 ?m,a density of 20.9 kg/m3,a compressive strength of 36.3 kPa,a compression modulus of 620 kPa,and a minimum buffer coefficient of 2.94,whose comprehensive performance was superior to the most commonly used buffer packaging materials.In a word,the process conditions and methods acquired through this research can not only achieve efficient conversion and utilization of agricultural and forestry byproduct biomass resources such as CF,but also obtained buffer packaging materials with better comprehensive performance while reducing petroleum-based materials.This provides an important solution for reducing dependence on petroleum resources and keeping green sustainable development.